Component Basics

Datasheets for electronic parts have become relatively easy to find on the internet. Here are a few of my favorite places to find spec sheets for electronic components:

http://www.alldatasheet.com/ - easy to use, straightforward search for a datasheet. One thing I like is that if you put in a part number like LM317T, it will return the results on the next page sorted by manufacturers. It also gives you a list of other similar part numbers and the option to search by other terms in the results just by clicking on the hyperlink.

http://www.datasheetcatalog.com/ - also easy to use. Less noise than alldatasheet because the results that are returned are only hyperlinked on the actual pdf file.

http://www.datasheetlocator.com/ - not as easy to use as the searches begin with the manufacturer, and sometimes you don’t know who the manufacturer is, BUT the best thing is that is will bring you right to the place on the manufacturer’s web site where you can search for datasheets. This is useful as long as the manufacturer hasn’t moved their datasheets to different files!

http://www.datasheetarchive.com/ - this is my least favorite of all the datasheet resource sites because of the way the results are returned. Very clunky and not intuitive because of the large number of ads on their site.

Sometimes with obsolete parts, finding a datasheet may prove elusive. When I can not find one on the major datasheet sites, I often turn to google. If you simply do a search by part number you are often presented with results of electronic component companies that don’t actually own the parts, don’t link you to a page other than a list of parts and don’t have any information about the parts. You can determine those results immediately by the sub-text listed in the google search engine results. If you see a list of part numbers like this, you know that more than like you won’t find the datasheet or other info there:

Most of the datasheets on the internet are in Adobe pdf format. So, you can refine your search on google by simply adding ‘.pdf’ (with or without the quotes is fine) to your search string. That will sometimes pop the datasheets up to the top for you. Another search query I use is “part number .pdf .edu”. The reason is that universities often have a nice store of datasheets.

Sometimes the only way is to go directly to the web site of the manufacturer and looking there. Very often their sites are so large that not every page gets indexed into the major search engines. While most of the datasheets can be found on the major datasheet resource sites, I have had luck many times on the manufacturer’s web sites, too.

Happy datasheet hunting!

The LM324AD is a readily available quad operational amplifier.

The LM324 series is a low−cost quad op amp with true differential inputs. It has a few notable benefits over regular operational amplifiers constructed in single supply applications. The quad op amp operates at voltages as low as 3V up to a high of 32V with quiescent currents about 1/5 of these associated with the MC1741 (on a per amplifier basis). The common mode input range includes the negative supply, thereby eliminating the necessity for external biasing components in many applications. The output voltage range also includes the negative power supply voltage.

The LM324 series is made using four internally compensated, two−stage operational amplifiers. The first stage of each consists of differential input devices Q20 and Q18 with input buffer transistors Q21 and Q17 and the differential to single ended converter Q3 and Q4. The first stage performs not only the first stage gain function but also performs the level shifting and transconductance reduction functions. By reducing the transconductance, a smaller compensation capacitor (only 5.0 pF) can be employed, thus saving chip area.

The transconductance reduction is accomplished by splitting the collectors of Q20 and Q18. Another feature of this input stage is that the input common mode range can include the negative supply or ground, in single supply operation, without saturating either the input devices or the differential to single−ended converter. The second stage consists of a standard current source load amplifier stage.

Each amplifier is biased from an internal−voltage regulator which has a low temperature coefficient thus giving each amplifier good temperature characteristics as well as excellent power supply rejection.

Electrolytic capacitors are constructed of high purity aluminum foil that has an aluminum oxide thin film dielectric on their surface. West Florida Components has a large selection of radial electrolytic capacitors in stock.

Here’s a list of the Radial Electrolytic Capacitors available.
0.22uF .22uF 50V Radial Electrolytic Capacitor CE-KD Series

0.22uF .22uF 50V Radial Electrolytic Capacitor EV.22M50AA

0.33uF .33uF 50V Radial Electrolytic Capacitor

0.47uF .47uF 50V Radial Electrolytic Capacitor HFS Series

0.47uF .47uF 50V Radial Electrolytic Capacitor Capar

0.47uF .47uF 50V Radial Electrolytic Capacitor Nichicon

0.47uF .47uF 50V Radial Electrolytic Capacitor RMRM Series

0.47uF .47uF 50V Radial Electrolytic Capacitor SME50VB0.47FM

0.47uF .47uF 50V Radial Electrolytic Capacitor Yeong-Long LTD

0.56uF .56uF 50V Radial Electrolytic Capacitor Richey

0.56uF .56uF 50V Radial Electrolytic Capacitor

1uF 50V Radial Electrolytic Capacitor UVX1H010MDA1CA

1uF 50V Radial Electrolytic Capacitor 5130105M050JA40SB

1uF 50V Radial Electrolytic Capacitor ECR Series

1uF 50V Radial Electrolytic Capacitor Elna

1uF 50V Radial Electrolytic Capacitor HFS Series

1uF 100V Radial Electrolytic Capacitor KME Series

1uF 100V Radial Electrolytic Capacitor

1uF 200V Radial Electrolytic Capacitor

1uF 315V Radial Electrolytic Capacitor CEUSM2F010A

1uF 350V Radial Electrolytic Capacitor NTE

1uF 350V Radial Electrolytic Capacitor

1uF 450V Radial Electrolytic Capacitor

2.2uF 50V Radial Electrolytic Capacitor NRSA2R2M50V

2.2uF 50V Radial Electrolytic Capacitor

2.2uF 100V Radial Electrolytic Capacitor

2.2uF 200V Radial Electrolytic Capacitor

2.2uF 250V Radial Electrolytic Capacitor UVR2ER2MEA1AA

2.2uF 250V Radial Electrolytic Capacitor

2.2uF 400V Radial Electrolytic Capacitor KME Series

3.3uF 63V Radial Electrolytic Capacitor 222203758338

3.3uF 100V Radial Electrolytic Capacitor 517D335M100JA7K

3.3uF 100V Radial Electrolytic Capacitor 517D335M100

3.3uF 160V Radial Electrolytic Capacitor

3.3uF 200V Radial Electrolytic Capacitor

3.3uF 350V Radial Electrolytic Capacitor 335RMR350M

3.3uF 450V Radial Electrolytic Capacitor

4.7uF 35V Radial Electrolytic Capacitor

4.7uF 25V Radial Electrolytic Capacitor

4.7uF 450V Radial Electrolytic Capacitors

4.7uF 50V Radial Electrolytic Capacitor 2038-034-36478

4.7uF 50V Radial Electrolytic Capacitor CE-SE Series

4.7uF 50V Radial Electrolytic Capacitor HFS Series

4.7uF 63V Radial Electrolytic Capacitor SME Series

4.7uF 100V Radial Electrolytic Capacitor 475CKR100M

4.7uF 160V Radial Electrolytic Capacitor CEBSM2C4R7M1-T4

4.7uF 200V Radial Electrolytic Capacitor UVX204R7MPA1TD

4.7uF 200V Radial Electrolytic Capacitor

4.7uF 315V Radial Electrolytic Capacitor 5150475M315CD7K

4.7uF 350V Radial Electrolytic Capacitor KME Series

4.7uF 400V Radial Electrolytic Capacitor 475CKH400M

6.8uF 25V Radial Electrolytic Capacitor

6.8uF 35V Radial Electrolytic Capacitor CRE Series

6.8uF 35V Radial Electrolytic Capacitor

10uF 16V Radial Electrolytic Capacitor 5150106M016JA6A

10uF 16V Radial Electrolytic Capacitor

10uF 350V Radial Electrolytic Capacitor

10uF 35V Radial Electrolytic Capacitor NRSA Series

10uF 35V Radial Electrolytic Capacitor UVR1V100MDA1TA

10uF 35V Radial Electrolytic Capacitor

10uF 35V Radial Electrolytic Capacitor 515D106M035
22uF 400V Radial Snap In Electrolytic Capacitor

22uF 450V Radial Electrolytic Capacitor

33uF 450V Radial Electrolytic Capacitor

100uF 16V Radial Electrolytic Capacitors

330uF 200V Radial Electrolytic Snap-In Capacitors KL20337M22035

330uF 385V Radial Electrolytic Capacitors B43502-D337-M90

470uF 400V Radial Electrolytic Snap-In Capacitors

560uF 160V Radial Electrolytic Capacitors

1000uF 100V Radial Electrolytic Snap-In Capacitors

Assorted Radial Electrolytic Capacitors 450V

A fuse is over current protection device, which breaks the circuit in case of an excessive current flow, thus protecting the other electronic components of the circuit from any damage that excessive current may cause. The fuse normally consists of a metal strip or wire that melts when excessive current starts flowing through it.

Fuses are integral parts of power distribution systems to prevent any damage or fire that may be caused as a result of excessive current passing through them.

Fuses are defined to be of two basic types - the slow blow and the fast acting.

The slow blow type of fuse has a coiled construction inside it. These fuses break the circuit only when the excessive current is continuous and not just a current surge. Short circuits are this type of continuous overload which are best protected by slow blow type of fuses.

In fact acting fuses, on the other hand, the fuse opens the circuit very quickly in case of any current surge, even if temporary. This is ideal or analog meter movements which can quickly get destroyed if excessive current flows through them. While a fast acting fuse may be used in place of a slow blow fuse, the reverse should not be done as the fuse may not break the circuit in time to protect the electronic components from damage.

Fuses are given different ratings to determine which fuse is best suited to a particular circuit or system. Rated current of the fuse gives the maximum current that can pass through the fuse without causing it to break the circuit. The I2t value measures the energy required to blow the fuse and indicates the energy that the circuit elements need to withstand before the fuse breaks the circuit.

Author Resource:- Andy Bauer is a tech writer for West Florida Components - an internet based retailer of electronic parts and supplies. Visit West Florida Components for a large selection of electronic components and guides.

Soldering is the process of joining two or more parts together with a fusible alloy, such as tin or lead, using a heated instrument called a soldering iron.

Soldered joints, if improperly done, may need to have the solder removed in order to re-solder them. A poor joint may result in complete failure of the electrical connection over a period of time. Poor quality of solder, improper cleaning of the surface before soldering, lack of correct technique, corrosion of the joint due to leftover flux, movement (shake) of the joint before the solder has cooled may all cause a poor soldered joint.

Re-soldering may also be required in order to replace a defective electronic component or to troubleshoot an electronics problem.

The process of removing solder and components is called desoldering.

There are a few common methods of desoldering. The two most commons techniques are described below. What they have in common is that both require the use of a soldering iron to complete the task.

A common method of desoldering is to use a desoldering pump that is a vacuum pump similar in operation to a bicycle pump, but in reverse. It has a spring-loaded plunger that breaks the solder and is sucked away by the pump. Repeated operation of the pump may be required in order to completely desolder a joint. The pump has to be operated carefully in order not to damage the PCB or the electronic component.

A solder wick or braid is an alternative to desoldering pumps. Here the copper wick is placed over the joint and the solder is melted by means of a soldering iron. The solder gradually flows into the wick and hence gets removed. The wick must be removed from the PCB before it cools down as otherwise it may damage the board.

Something you might want to take into consideration is that solder wick is the more expensive alternative so if you need to do a lot of desoldering, you may want to use the solder pump as your primary method, then use the solder wick to complete the task.

It is recommended that a soldering iron in the 15W to 30W range be used. Soldering irons with higher wattage may result in damage to the board or components, however some heavier connections (like a chassis) may require a higher wattage iron to properly remove all the solder.

Take precautions when working with solder. Do your work in a well-ventilated area as fumes from the resin can get into your lungs or eyes. Be careful not to let the hot solder splash you. You could get severely burned. Lastly, consider using eye protection such as work goggles when working with solder.

Desoldering is not as difficult as you might think. Take heed of the precautions and follow the suggested methods for an easy desoldering experience.

Author Resource:- Andy Bauer is a tech writer for West Florida Components - an internet based retailer of electronic parts and supplies. Visit West Florida Components for a large selection of electronic components and guides.

When selecting a switch, you can ensure that the most appropriate switch is chosen if you take these factors into consideration.

End user requirements:

The designer should consider the conditions under which a switch will be used. For example, whether the user requires an on/on switch or an on/off switch, and if illumination or legends are required to indicate the status are both things that should be considered.

The ease of use of the various switch design types and sizes available need to be questioned during the selection process. A good rule of thumb is that the switch that not only meets the other requirements, but is easy to use, should be chosen.

Engineering specifications:

The engineering aspects of the switch must be assessed in order to ensure that it is able to carry out the expected functions. The load characteristic is an important aspect of any switch selection and will impact the type of switch that can be chosen. Factors like size are important. Switches can be standard, miniature, or sub miniature. Also consider mounting limitations like PC mount, surface mount, solder or fast connect when selecting a switch for your application.

It also matters whether the switch is a momentary switch or continuous contact or maintained switch. A momentary switch keeps the circuit closed or open for a very short period of time while the continuous or maintained switch keeps it open or closed for long periods of time.

The type of contact material is another factor to be considered when choosing a switch. Silver is the most commonly used material for the contacts as it is a good conductor and hence has low resistance. Gold is generally used when switching is performed at logic level (1-100mA).

The longevity and quality of a switch is another important factor. Low quality switches cost less initially but maintenance and replacement costs can make it more costly in the end. Momentary switches have longer life as compared to maintained switches.

Type of actuator:

There are a variety of actuator types available for switches to meet varying demands.

Push button switches are a very common type of switch used in a wide variety of applications. They may be momentary or maintained, illuminated or non-illuminated and are available in several shapes and sizes.

Another common type of switch is the rotary switch where the switch is rotated to choose a particular circuit combination and is available in wide range of sizes and types. It may be sub-miniature dip rotary, very large or heavy duty rotary. It may also be enclosed or open deck type and have many stop positions and poles.

A type of rotary switch is a key lock switch, which can be of low, medium or high security. There are also many key options, sizes and circuits available in key lock switches.

Slide actuated switches are a special type of switch used in certain applications. They are also available in several sizes, key choices and circuit functions.

Toggle switches, rockers and paddle switches are also available in many different sizes and ratings. They may also be momentary or maintained, illuminated or non-illuminated. In addition they can also have 2 or 3 positions.

Standards and government regulations:

Does your application require that switches be certified by UL and CSA? Ratings like the UL94V specifies the fire retardant characteristics of a switch while TV5 and TV8 ratings are related to the arc proof characteristics. These ratings are aimed at ensuring that the switches meet the needs of a given application.

Ratings like the IP rating helps in choosing the right type of switch for a given application. For example, IP 65 rated switches provide protection against dust and high pressure water sprays while an IP 67 rated switch is protected from temporary immersion up to 1m deep water.

Compliance with relevant standards and government regulations is another issue to be considered. Acts like the Resource Conservation and Recovery Act (RCRA), the Clean Water Act and the Clean Air Act (CAA) are some of the regulations to be followed. In addition, European countries follow regulations like RoHS and Waste Electrical Electronic Equipment (WEEE) that limit the use of hazardous chemicals in manufacture of goods.

Operating environment:

The condition of the environment or surroundings under which the switch operates is also an important consideration when deciding on a particular type of switch. Factors like temperature, humidity, dust etc. influence the working of a switch. Applications like medical devices, marine equipment, harsh industrial environment, construction / mining etc. require special type of switches suited to the environment under which the equipment operates.

Using these guidelines can aid you in making the correct choice of switch for an application. By following them, you can quickly come to a conclusion about whether a switch is suited for a particular application or not. Remember that switches are an important part of any application. Making the correct choice of switch will save time and money by avoiding unnecessary maintenance or replacement later and enhance customer satisfaction.

Author Resource: Andy Bauer is a tech writer for West Florida Components - an internet based retailer of electronic parts and supplies. Visit West Florida Components for a large selection of electronic components including switches.